1. Field of the Invention
The invention relates to carrier plates and, more particularly, to carrier plates for electronic components having improved thermal characteristics.
2. Description of the Related Art
A number of commercially important products employ a metal plate of some sort and require various features to be added to the metal plate. For example, assembly substrates sometimes need to be provided with upstanding locking lugs, standoffs, or threaded studs. While these features can be provided in the form of separately fabricated components, a problem arises as to the need for securely fastening these features to the substrate. In addition to mechanical type fasteners, metallurgical bonds such as soldering and brazing need to be formed on a metal substrate for purposes of joining various components to the substrate. One commercially important example of this type of joinder is found in the manufacture of high power radio frequency circuits, where circuit boards of relatively expensive materials are soldered to carrier plates providing a ground path and heat sink for the circuit boards.
Many commercially important high power radio frequency circuits are presently constructed using expensive ceramic circuit boards that are soldered to carriers made of costly graphite or AlSiC materials. The carrier not only provides physical support for the circuit board but also a much needed heat spreading and heat sink and a ground path for electronic devices carried on the circuit boards. It is important that the circuit boards and their carriers provide an efficient thermal conduction circuit in order to extend the life and improve the operating characteristics of the heat-generating electronic devices. Since substantial heat loading is expected to be encountered in many of these types of circuits, it is important that the circuit board and carrier be well matched with regard to their respective co-efficient of thermal expansion.
Accordingly, there is a need for an improved carrier plate in terms of both its performance and costs therefor. In particular, there is a need for a carrier plate for electronic power components, e.g. power transistors, that can employ lower cost materials and be efficiently manufactured.